Jun Wang¹, Wei Huang², Raghbir S. Bhullar³, Pin Tong²

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 161-168, 2004, DOI:10.3970/mcb.2004.001.161

Abstract Surface-tension-driven blood flow into a capillary tube, as in some medical devices, is studied. In a previous article, we considered the early stages of the entry flow from a drop of blood into a capillary, and solved the problem analytically under the assumption that the resistance of the air is negligible. In the present note we consider a capillary tube of finite length, with the far end containing a small window which opens to the atmosphere. The dynamic reverberation of the air in the capillary tube is analyzed in conjunction with the dynamics of the… More >

K.Y. Volokh¹

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 147-160, 2004, DOI:10.3970/mcb.2004.001.147

Abstract A simple phenomenological framework for modeling growth of living tissues is proposed. Growth is defined as a change of mass and configuration of the tissue. Tissue is considered as an open system where mass conservation is violated and the full-scale mass balance is applied. A possible structure of constitutive equations is discussed with reference tosimple growing materials. 'Thermoelastic' formulation of the simple growing material is specified. Within this framework traction free growth of cylindrical and spherical bodies is examined. It is shown that the theory accommodates the case where stresses are not generated in uniform More >

A. Tsourkas, R. Weissleder^1,1

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 133-146, 2004, DOI:10.3970/mcb.2004.001.133

Abstract Traditionally, fluorescent and luminescent reporter proteins have been used as indicators of gene expression and protein localization. However, insightful mutagenesis and protein engineering strategies have transformed these simple passive reporters into active biological sensors. Molecular reporters are now being designed to alter their intrinsic optical properties in response to specific biomolecular interactions. Applications for these novel biological sensors range from monitoring intracellular pH and ion fluxes to detecting protein-protein interactions and enzymatic activity. The ability to monitor the dynamics of intracellular activity in response to external stimuli can help elucidate the cascade of events involved More >

Kathleen Puskar¹, Leonard Apeltsin², Shlomo Ta’asan³, Russell Schwartz², Philip R. LeDuc⁴

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 123-132, 2004, DOI:10.3970/mcb.2004.001.123

Abstract Understanding the connection between mechanics and cell structure requires the exploration of the key molecular constituents responsible for cell shape and motility. One of these molecular bridges is the cytoskeleton, which is involved with intracellular organization and mechanotransduction. In order to examine the structure in cells, we have developed a computational technique that is able to probe the self-assembly of actin filaments through a lattice based Monte Carlo method. We have modeled the polymerization of these filaments based upon the interactions of globular actin through a probabilistic model encompassing both inert and active proteins. The More >

Daxiang Cui¹, Cengiz S. Ozkan², Sathyajith Ravindran³, Yong Kong¹, Huajian Gao¹

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 113-122, 2004, DOI:10.3970/mcb.2004.001.113

Abstract Experiments on encapsulating Pt--labelled DNA molecules inside multiwalled carbon nanotubes (MWCNT) were performed under temperature and pressure conditions of 400K and 3 Bar. The DNA-CNT hybrids were purified via agarose gel electrophoresis and analyzed via high resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that the Pt-labelled DNA molecules attached to the outside walls of CNTs could be removed by electrophoresis. The HR-TEM and EDX results demonstrated that 2-3% of the Pt-labelled DNA molecules were successfully encapsulated inside the MWCNTs. The experimental study complements our previous molecular dynamics simulations More >

M.V. Bayas^1,1, K.Schulten^2,2, D. Leckb,^3,3

Molecular & Cellular Biomechanics, Vol.1, No.2, pp. 101-112, 2004, DOI:10.3970/mcb.2004.001.101

Abstract The force-induced dissociation of the strand dimer interface in C-cadherin has been studied using steered molecular dynamics simulations. The dissociation occurred, without domain unraveling, after the extraction of the conserved trypthophans (Trp2) from their respective hydrophobic pockets. The simulations revealed two stable positions for the Trp2 side chain inside the pocket. The most internal stable position involved a hydrogen bond between the ring Ne of Trp2 and the backbone carbonyl of Glu90. In the second stable position, the aromatic ring is located at the pocket entrance. After extracting the two tryptophans from their pockets, the More >

Leo Q. Wan^1,1, Chester Miller^1,1, X. Edward Guo^2,2, Van C. Mow^1,1,3,3

Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 81-100, 2004, DOI:10.3970/mcb.2004.001.081

Abstract The triphasic constitutive law [Lai, Hou and Mow (1991)] has been shown in some special 1D cases to successfully model the deformational and transport behaviors of charged-hydrated, porous-permeable, soft biological tissues, as typified by articular cartilage. Due to nonlinearities and other mathematical complexities of these equations, few problems for the deformation of such materials have ever been solved analytically. Using a perturbation procedure, we have linearized the triphasic equations with respect to a small imposed axial compressive strain, and obtained an equilibrium solution, as well as a short-time boundary layer solution for the mechano- electrochemical… More >

Jessica E. Koehne, Jun Li¹, Alan M. Cassell, Hua Chen, Qi Ye, Jie Han, M. Meyyappan

Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 69-80, 2004, DOI:10.3970/mcb.2004.001.069

Abstract Vertically aligned multi-walled carbon nanotubes (MWCNTs) have been reported in fabricating nanoelectrode arrays. Further studies on optimizing this system for the development of ultrasensitive DNA sensors are reported here. The mechanical stability of the as-grown MWCNT array can be improved by polymer coating or SiO₂ encapsulation. The latter method provides excellent electronic and ionic insulation to the sidewall of MWCNTs and the underlying metal layer, which is investigated with electrochemical impedance spectroscopy. The insulation ensures well-defined nanoelectrode behavior. A method is developed for selectively functionalizing biomolecules at the open end of MWCNTs while keeping the SiO₂ More >

D.E. Ingber¹

Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 53-68, 2004, DOI:10.3970/mcb.2004.001.053

Abstract This article is a summary of a lecture presented at a symposium on "Mechanics and Chemistry of Biosystems'' in honor of Professor Y.C. Fung that convened at the University of California, Irvine in February 2004. The article reviews work from our laboratory that focuses on the mechanism by which mechanical and chemical signals interplay to control how individual cells decide whether to grow, differentiate, move, or die, and thereby promote pattern formation during tissue morphogenesis. Pursuit of this challenge has required development and application of new microtechnologies, theoretical formulations, computational models and bioinformatics tools. These… More >

Huajian Gao^1,1, Baohua Ji^1,1, Markus J. Buehler^1,1, Haimin Yao^1,1

Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 37-52, 2004, DOI:10.3970/mcb.2004.001.037

Abstract Bone-like biological materials have achieved superior mechanical properties through hierarchical composite structures of mineral and protein. Gecko and many insects have evolved hierarchical surface structures to achieve extraordinary adhesion capabilities. We show that the nanometer scale plays a key role in allowing these biological systems to achieve their superior properties. We suggest that the principle of flaw tolerance may have had an overarching influence on the evolution of the bulk nanostructure of bone-like materials and the surface nanostructure of gecko-like animal species. We demonstrate that the nanoscale sizes allow the mineral nanoparticles in bone to More >